Record wave 4's landed coverage, and that the hang watchdog has fired

Numbers re-measured on 6004398 rather than inherited: 94.2% line (2234/2372),
87.5% branch (1171/1338), 628 tests in 96 classes, missed 138 lines and 167
branches.

The entry explains its own branch move, because this file has a history of not
doing that. Wave 4's rise is almost entirely numerator -- up 80, with the
denominator moving -4 -- unlike the 2026-08-29 seam work, where the numerator
rose 37 while the denominator fell 70 and much of the gain was scaffolding
leaving the measurement. The line denominator grew 20, which is the seams the
wave cut rather than untested code.

Also records a methodological result worth more than the percentages: #218 fixed
an intermittent flake whose six-runs-per-arm comparison caught nothing either way
and proved nothing, and was settled by a deterministic mutation instead -- then
confirmed when the race reproduced on #217's leg, below the fix.

The JUnit-timeout trap gains the outcome it was waiting for: the jstack watchdog
caught #125's Room/WorkManager deadlock on CI in 10m57s with the hung test named,
against that ticket's prediction of a 60-minute cap and no cause. #125 is closed
as bounded; the inversion is internal to the two libraries and still live at
work-runtime 2.11.2 / room 2.7.0.

Instrumented counts are untouched: #221 is what changes them, so it carries them.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -130,9 +130,9 @@ install for code that can never run — and on API 37 the full APK does not fit
 - The `model` package is excluded from `ReturnCount` and `CyclomaticComplexMethod` only. It is the
   decision layer, where one branch is one documented user-visible outcome and the metric counts
   answers rather than complexity. Every other rule still applies there.
-- **Coverage is reported, not gated** — **92.8% of lines (2183/2352), 81.3% of branches
-  (1091/1342)**, measured 2026-09-02 with `./gradlew :app:jacocoTestReport`, against 584 JVM tests
-  in 87 classes.
+- **Coverage is reported, not gated** — **94.2% of lines (2234/2372), 87.5% of branches
+  (1171/1338)**, measured 2026-09-05 with `./gradlew :app:jacocoTestReport`, against 628 JVM tests
+  in 96 classes.
 
   **Every figure this file carried before 2026-08-24 was an artifact, roughly half the real one.**
   Robolectric loads classes through its own sandbox classloader with no source location, JaCoCo
@@ -283,6 +283,33 @@ install for code that can never run — and on API 37 the full APK does not fit
   #194 before re-arguing either way — and note the reason it is worth cutting is not coverage but
   that the `runCatching` fallback logs "assuming permissive" while returning empty sets, which makes
   `canEncode` and `canDecode` answer *no* for everything.
+
+  **Wave 4's tests then landed on 2026-09-05**, as #206-#217 for the twelve tickets plus #218
+  (#159) and #219 (#122): 92.8% -> **94.2%** line, 81.3% -> **87.5%** branch, 584 -> 628 tests in 87
+  -> 96 classes. Missed lines 169 -> 138, missed branches 251 -> 167.
+
+  **Its branch move is a different animal from the 2026-08-29 seam work's, and the difference is the
+  point.** That one gained 6.3 branch points with the numerator up 37 (974 -> 1011) while the
+  denominator *fell* 70 (1410 -> 1340) — much of the rise was scaffolding leaving the measurement
+  rather than arms being covered. Here the numerator is up **80** (1091 -> 1171) and
+  the denominator moved **-4** (1342 -> 1338). So this one is almost entirely tests choosing arms
+  nothing had chosen, which is what the entry above warns to check before quoting a branch figure.
+  The line denominator rose the other way, 2352 -> 2372, and that is new production code rather than
+  untested code: the seams the wave cut — `capabilitiesFrom`, `ffprobeInfoFrom`, `sessionOutcome`,
+  and `sweepScope`/`startupSweep`.
+
+  **The two-filter method above is what found the work**, and its second filter earned its place:
+  the largest single gap of the wave (#192, the Cancel button never shown to reach WorkManager) sits
+  on lines that were already green and no line-level filter could see it.
+
+  One result worth carrying forward about *evidence* rather than coverage. #218 fixed a flake whose
+  reproduction is statistical, and running the whole suite six times per arm caught nothing either
+  way — at the observed rate a clean six-run arm is roughly a coin flip, so the comparison was
+  underpowered and proved nothing. What settled it was a deterministic mutation, and then the merge
+  train confirmed it by accident: the race reproduced on #217's Unit tests leg, which sits below
+  #218 and carries the unfixed scope. **Prefer a mutation that must go red to a repetition count**
+  when a fix is for something intermittent.
+
 - **Testable code is not done until it is tested.** If a piece is unit testable, it gets unit
   tests before it counts as done. If it is e2e testable, it gets e2e tests. Both clauses apply —
   a change that is both needs both.
@@ -410,7 +437,11 @@ Because versions float, a build can change without a commit. `./gradlew :app:dep
   run instead is `timeout` on the `Test` tasks plus the jstack watchdog beside it in
   `app/build.gradle.kts`, neither of which moves a thread. `HangBoundTest` guards both numbers,
   and **a timed-out run writes no XML for the class that hung** — the dump is its only
-  attribution, so do not delete the watchdog as stray config.
+  attribution, so do not delete the watchdog as stray config. It has since been exercised in anger:
+  on 2026-09-05 it caught #125's Room/WorkManager deadlock on CI, failing in 10m57s with the hung
+  test named, where that ticket had predicted a 60-minute cap and no cause. #125 is closed as
+  bounded on the strength of it — the inversion itself is internal to the two libraries and still
+  live at `work-runtime` 2.11.2 / `room` 2.7.0.
 - **The JVM suite does not run `LibreMediaConverterApp`.** `app/src/test/resources/robolectric.properties`
   names `TestLibreMediaConverterApp` for every test, and it differs from the real class in exactly
   one thing: `sweepScope` is `Dispatchers.Unconfined`, so the startup staging sweep finishes before